Long-term biomass yields of giant reed, mimosa and switchgrass in Alabama



The US Department of Energy conducted two studies to estimate the potential of cellulosic biomass crops for production of biofuels on a national scale. However, limited long-term experimental information is available to support the resultant yield projections. The objectives of this research were: (i) to determine long-term (>10 years) biomass yields and soil impacts of switchgrass (Panicum virgatum L.), giant reed (Arundo donax L.) and mimosa (Albizia julibrissin Durazz.) in Alabama; and (ii) to establish relationships between precipitation and yields of these perennial biomass crops, and yields of cotton, maize, and soybean. Mimosa and giant reed received no fertilizer and were harvested once each year while switchgrass received 84 kg ha–1 of N fertilizer annually, and was harvested twice each year. Cotton, maize, and soybean were managed according to traditional practices for these crops in this region. Average annual biomass yields of mimosa, giant reed, and switchgrass were 40.1, 35.5 and 23.5 kg ha–1 over 16-, 11- and 22-year periods, respectively, with corresponding estimated annual N accumulation in aboveground biomass of 388, 372 and 163 kg ha–1. Yields of maize, cotton and soybean decreased sharply with decreasing precipitation, but there was no corresponding decrease in yield of the three perennial biomass crops. Changes in the yields of the biomass crops with age were also relatively small. Analysis of topsoil samples suggested considerably less removal of P, K, Ca, and Mg than was estimated from yield and concentrations of these elements in the biomass that was actually removed. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd